The cutaneous pigmentation of mammals in general, and of man in particular, is based on the biosynthesis of a nitrogenous pigment, melanin, from tyrosine, whose regulation is under the influence of several parameters:
tyrosinase, produced by the pigment cell, PA1 the melanocyte, which under the influence of ultraviolet light catalyses the oxidation of tyrosine to dihydroxyphenylalanine (DOPA), then to dihydroxyindole and finally to melanin, PA1 the melanin can then be subjected to oxidative polymerizations which will accentuate its coloration; this pigment is present in the form of organelles, the melanosomes, in the dendrites of the abovementioned melanocytes and these melanosomes are then transmitted to the keratinocytes, which transport the melanin to the surface of the skin where it is progressively eliminated during natural desquamation. PA1 it has a tanning power at daily doses of .beta.-carotene significantly lower than those used earlier to this effect and not exceeding the limits recommended in the abovementioned Directive, and PA1 it has, at the same time, a tanning power and an active photoprotective effect on account of the fact that it especially induces the production of eumelanin.
The melanin formed is composed of two types, (1) eumelanin, which is a black-brown color and is formed by polymerization of oxidation products of dopaquinone and (2) pheomelanin which is a reddish-brown color and is formed by polymerization of sulfur derivatives of dopaquinone; only the first type has a photoprotective effect.
The color of the skin and its intensity thus depend on the melanin content of the keratinocytes, on the type of melanin present in these keratinocytes, on the rate of desquamation and on the thickness of the horny layer which is the layer containing the most pigment.
Essentially for cosmetic reasons, man exposes himself more and more to the sun, in order to have a tanned skin.
However, ultraviolet radiation (UVA and UVB), usually proposed for tanning (sunlamps, for example), have short term as well as long term dangers.
In addition, because of a progressive decrease in the ozone layer, the deleterious effects of ultraviolet solar radiation require the photoprotection of individuals to be increased.
To combat the harmful short-term effects of ultraviolet radiation, namely solar erythema and photosensitization, it is necessary to protect the skin.
However, all of the products for oral administration proposed in the prior art are uniquely centered on the cosmetic effect: obtainment of a "tanned" skin, and comprise the administration of .beta.-carotene at doses clearly higher than those recommended in EEC Directive 90/496, namely 800 .mu.g/day, expressed as vitamin A, or 6 mg of .beta.-carotene/day.
At the doses usually used in these products from the prior art, that is to say of the order of 12 to 30 mg/day, there is accumulation of .beta.-carotene in the keratinocytes, which gives the skin an appearance of "tanning", but does not allow it to have, in addition, active photoprotection by induction of eumelanin, during subsequent exposure to the sun.
Consequently, the Applicant has especially aimed at providing a composition which can be administered by the oral route and which responds better to the needs of practice than the compositions of the prior art, especially in that:
The present invention relates to a composition for cosmetic purposes, which is a regulator of cutaneous pigmentation and is adapted both to administration by the oral route and to application on the skin, of the type comprising carotenoids, characterized in that it essentially comprises a component (a) formed of at least one carotenoid of natural origin with provitamin A activity selected from the group consisting of .beta.-carotene and .alpha.-carotene or a mixture of these, and a component (b), corresponding to at least one carotenoid of natural origin without provitamin A activity, formed by lycopene, optionally associated with another component (b), selected from the group consisting of zeaxanthin, cryptoxanthin and lutein or a mixture of these, the components (a) and the lycopene being in a ratio of between 0.95:1 and 1:50.
Pigmentation regulator, in the sense of the present invention, is understood as meaning an active principle having tanning power, that is to say inducing the endogenous synthesis of melanins.
Surprisingly, at ratios of components (a):lycopene lower than 1, both the composition intended for administration by the oral route and the composition intended to be applied on the skin have a tanning power without exposure to the sun and a photoprotective effect, during subsequent exposure to the sun.
Although the Applicant has found, surprisingly, that the composition intended for administration by the oral route, at daily doses of .beta.-carotene significantly lower than those used previously, has a tanning power and a photoprotective effect when said (a)/lycopene ratio is lower than 1 and preferably of between 0.95:1 and 1:50, there is no limitation of doses for the compositions fit to be applied by the topical route, which comprise the same components (a) and lycopene, in the same ratios as those defined for the compositions administered by the oral route.